Method of preserving wood.



l barman smarts Parana canton;

HANS FOERSTERLING, RALPH NELSON SARGENT, AND FREDERICK ALBERT KAUF- MANN, OF PERTH AMBOY, NEW JERSEY, ASSIGNORS TO THE ROESSLER & HASS-.

LACHER CHEMICAL CO., OF NEW YORK, N. Y., A CORPORATION OF NEW YORK.

METHOD OF PRESERVING.WOOD.

No Drawing.

To all whom it may Concern:

Be it known that we, HANS FOERSTERLING, I

a subject of the Emperor of Germany, RALPH NELSON SARGENT, a citizen of the United States of America, and FREDERICK ALBERT KAUFMANN, a subject of the Emperor of Germany, all residing at Perth Amboy, in the county of Middlesex and State of New Jersey, have invented certain new and useful Improvements in Methods of Preserving Wood, of which the following is a specification;

The object of the invention is the produc tion of a chemical compound adapted to act as a preserving agent within the wood by means of which decay caused by bacterial, fungi, insects and like undesirable forms of lower life, is retarded. To attain this purpose, certain chemicals, forming a desirable preserving agent, are caused to successively enter the pores of the wood.

We are aware that various chemicals have been tried in the art of preserving wood, but of these only creosote and solutions of zinc and mercury salts have been ,found of value and the use of even these agents is not free from disadvantagealthough they are somewhat successful in destroying the bacteria. and other agents harmful to vegetable life. In the case of zinc chlorid for instance, this is due to its solubility in water, causing the salt to leach out of the wood through moisture. Inthe case of mercury chlorid for instance, its high price has rendered its use almost prohibitive, while creosote, though insoluble in water and relatively low in price, has an antiseptic power less than that of zinc chlorid. This latter disadvantage is compensated to some extent by injecting a larger quantity into the wood, for instance 6 to 12 lbs. per cubic foot. But as zinc chlorid is used in such a small quantity as lb. per cubic foot, the use of such a large amount of creosote makes the creosote rocess more expensive than the zinc ch orid process.

In our research work on this subject we have found that an ideal woodpreserving agent should possess the following essential qualities; it should be ant1septic, i. 0., it must destroy all forms of lower animal and vegetable life contributing to the decay of the wood; it should retain its antiseptic qualities for along period of'time; it should Specification of Letters Patent.

these requirements better Patented Oct. a, ram.

Application filed December 27, 1915. Serial No. 68,623.

be insoluble in water and should be reasonably cheap. We have found that copper cyanid is a preserving agent answering than any other compound. As copper cyanid is insoluble in water, it must be produced either inside the wood by a double decomposition between a cyanid solution and that of another chemical, as for instance between a sodium cyanid and a copper sulfate solution, or it must bedeposited in the intercellular spaces of the wood by impregnating the wood with a solution containing copper cyanid and subsequently precipitating the copper cyanid out of solution by some agent. Such a solution suitable for our purpose is obtained by dissolving copper cyanid in an alkali cyanid, ammonia, oil or composition of oils, etc., while as a precipitating agent we prefer to use either water or inorganic as well as organic acids, and of the latter especially those contained in the wood, or the ligneous juices of the wood. Any other suitable precipitating agent may of course be used.

. The method we prefer, in practising our invention, consists 1n first impregnating the wood with a solution of one of the chemicals by the usual mechanical methods of bringing about such' impregnation, and subsequently similarly treating the same with the solution of the other chemical to bring about the double decomposition to form copper cyanid. It wasnoted, however, in case wood of some thickness is treated that after treating the wood first with sodium cyanid solution, for example, the copper sulfate solution did not penetrate it as far as the sodiumcyanid solution unless considerable pressure was applied. We prefer,

therefore, to first apply the copper sulfate solution and after this has thoroughly penetrated the wood to subsequently apply the sodium cyanid solution.

It is of course understood that we are not restricted to the use of sodium cyanid and copper sulfate for the production of the copper cyanid within the wood, but that our invention includes the use of any solution of a cyanid and of a copper compound which by their interaction within the wood will produce the desired copper-cyanid compound. In the example given below we describe the use of sodium cyanid and copper sulfate solution, as an illustration only and because we believe them best suited to bring about the desired efiect as well as because they are practicable. as far as their price is concerned. Furthermore, we wish to state that we do not consider ourselves restricted to the use of copper cyanid exclusively, as other cyanid compounds which are insoluble in water, as for instance zinc cyanid, answer the purpose and requirements of our process as well.

For the better understanding of our invention and to enable any one skilled in the art to understand the same, we shall describe, by way of example, one method of how we proceed on a small scale to carry our invention into eflect.

We place pieces of chestnut and oak, 4X4x8 in a pressed steel, copper-lined pot of 8 X14 dimensions, close the pot tightly and evacuate it, maintaining a vacuum of for three hours, to remove the air from the wood pores. A 1% solution of copper sulfate is then admitted so as to fill the pot. The contents of the pot are. now subjected to an air pressure of 50-60 lbs. for three hours. The pressure 15 1 then released, and the excess of the solution a large scale removed, while vacuum is applied to the pot for one hour; finally a 1% sodium cyanid solution is run into the pot and the contents again put under an air pressure of 50'60 lbs. for about three hours.

The interaction between the copper sulfate and the sodium cyanid solution pre-' cipitates insoluble copper cyanid, which is thus deposited in the intercellular spaces of the wood.

After the sodium cyanid has exerted its action on the wood saturated with the copper sulfate under the conditions stated above, it is run OH, and the pot is opened to take out the wood which is finished by drying in the usual way.

The time of operation depends of course on the kind of wood to be treated by our process, as soft wood is penetrated by the solutions more easily than hardwood. Furthermore the dimensions of the wood submitted to preservation processes vary considerably and the pressure to be applied on will therefore likewise vary.

The advantages of our process are selfevident. The quantities of chemicals needed to producethe precipitate of copper cyanid within the wood are so small that the cost of our new process is no higher than the e per cyanid per messes cost of the zinc chlorid process. As to the efiiciency of our process in destroying bacteria and other obnoxious agents it is superior to any other process because both the chemicals applied have antiseptic powers. As the antiseptic power of sodium cyanid may be assumed to be at least equal to that of corrosive sublimate it is usually sufficient to impregnate the wood with 1 oz. of copcubic foot of wood, this quantity corresponding to that of corrosive sublimate generally applied per one cubic foot of wood.

Furthermore as the precipitate of copper cyanid is insoluble in water it is superior to the processes in which the wood is treated with zinc chlorid or mercury chlorid as these latter, in course of time, both leach out by moisture; our process is also superior to the treatment of wood with creosote because of the great infiammability and smell of creosoted wood whereas our process renders the wood much less readily ignitable.

We claim:

1. The method of preserving wood, consisting in precipitating an insoluble ni etlal cyanid within the intercellular spaces 0 wood.

2. The method of preserving wood, consisting in precipitating copper cyanid within the intercellular spaces of the wood.

8. The method of preserving wood, consisting in precipitating copper cyanid within the intercellular spaces of the wood by the interaction of the solutionsof a cyanid and of a copper salt caused to successively enter the wood.

t. The method of preserving wood, consisting in precipitating copper cyanid within the intercellular spaces of the wood, by first causing a solution of a copper salt and subsequently of a cyanid to enter the wood.

5. The method of preserving wood, consisting in precipitaing copper cyanid within the intercellular spaces of the wood by first causing a solution of copper-sulfate and subsequently that of sodium cyanid to enter the wood.

In testimony whereof we have signed this specification in the presence of two subscribing witnesses;

HANS FOERSTERLING. RALPH NELSON SARGENT. FREDERICK ALBERT KAUFMANN. Witnesses:

v MARION SULLIVAN,

Orro K. ZWINGENBERGER. 

